<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(item,ind) in arr" :key="ind">{{item["name"]}}<button @click="btn(ind)">买书</button></li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(item,index) in arr" :key ="index">
        <td>{{index +1}}</td>
        <td>{{item ["name"]}}</td>
        <td>{{item ['price']}}</td>
        <td>{{item ['count']}}</td>
        <td>{{item ['count' ] *item ['price']}}</td>

        

        </tr>
    </table>
    <p>总价格为:{{allprice}} </p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods:{
    btn(index){
      this.arr[index]["count"]++
    }
  },
  computed:{
    allprice(){
     return  this.arr.reduce((sum,obj)=>{
    return  sum += obj['count' ] *obj['price']
    },0)
    }
    
  }
};
</script>